Paving method



June 2, 1931.

J. F. WITT PAVING METHOD Filed Jan. 30, 1930 2 Sheets-Sheet l June 2, 1931.

PAVING METHOD Filed Jan. 50, 1930 2 Sheets-Sheet 2 u M "b m,

I J. F. WITT 1,807,947

Patented June 2, 1931 PATENT "OFFICE JACKSON F. WI'IT, OF DALLAS, TEXAS PAVING METHOD Application filed January 30, 1930. Serial No.-424,609.

spread to a unlform thickness but so maintained even on crowned roads.

A further object of the invention is to so 1 interlock the liquid asphalt layer as to prevent creeping or disintegration of said layer. Another object of the invention is to em bed the liquid asphalt 'in depressions in the supporting course, whereby the paving is tied together, the cohesion enhanced and the wearing surface increased.

A construction designed to carry out the invention will be hereinafter described together with other features of the invention. 0 The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings in which an example of the invention is shown, and wherein:

Figurel is a transverse sectional view of a supporting course ready for carrying out'my improved method.

Figure 2 is a similar View priming coat applied.

Figure 3 shows the same after the puncturing or penetrating step.

Figure 4 is a transverse sectional view of a finished pavement.

Figure 5 is an enlarged sectional detail of its finished pavement.

Figure 6 is an isometrical view of a tool used in the method, and

Figure 7 is a transverse sectional view of a 4.0 modified form of pavement.

In carrying out the method a supporting course A is first built up in the usual manner. This course may be of any soft or semi-soft material, such as soft limestone,

caliche, water-bound. macadam, gravel or showing the shell foundation or any other material capable of being punctured or indented.

IV here the'cours-e is of clay formation'or materials which become glazed when rolled, it is necessary to scrape the surface sufficiently to leave a granular or saw-tooth top. This may constitute the first step of the method or it may not be necessary as where soft limestone is used.

, With the top surface of the course A prepared, a suitable hot liquid asphalt or asphaltic road oil is sprayed or. spread over the said surface to form a prime coat or layer B. I v

This coat is comparatively thin, one-quarter of an inch having been found satisfactory, but the invention is not to be limited to this measurement. 7

Immediately after the liqud asphalt is applied, there willbe spread or cast over the entire surface of said prime coat, either pea gravel, coarse sand or limestone screenings or the like in sufficient quantity to absorb the free liquid asphalt on the surface of the coat. The next step consists in rolling the surface of the coat B with a suitable roller, whereby it is smoothed and the mineral aggregate is embedded therein. I

The prime coat B is now ready for the next step, which consists in puncturing or penetrating the coat and indenting the sur-. face of the course A. v

In Figure 6 I have shown a roller 10 having conical studs or points 11 on its cylindrical surface. These studs are preferably arranged in circumferential rows, and those of one row in staggered relation to those of the adjacent rows.

By giving the studs a suitable length or projection from the face of the roller they not only penetrate the coat B, when rolled thereover, but indent the surface of the course A as is shown in. Figure 3. Any. other suitable tool may be used so long as the. coat B is punctured. If the asphaltic oil should tend to flow to the sides of pavement the sumps C will intercept it and thus prevent segregation of the base oils.

The next step consists in spraying or spreading over the prime coat B hot liquid asphalt or asphalt-i0 road oil so as to accumulate to a thickness preferably greater than that of the prime coat and form a top layer or course D. Good results have been had with a layer one-half of an inch thick, but this measurement is optional.

When the course D is applied; the asphaltic oil will flow down through the openings in the prime coat and fill the sumps- 0, thus forming inverted cones 111, depending from. the top coarse. Asphalt having an 'aflinity for itself, it is obvious that the cones illiad here to the prime coat, whereby the cohesion of the asphaltic oils will. be. setup. The coat B and course D will be interlocked thus hold ing them in place, and preventing disintegration.

' After the course D is applied, pea gravel,

limestone screenings or other fine mineral aggregate is spread over the surface. This is followed by rolling the surface until its free asphalt is absorbed, after which the pavement may be thrownopen to traffic. The cones E extending down into the course A and being on comparatively close centersprovide an adequate support and increase'the wearing surface as well as preventing creep,- ing or buckling of the pavement.

In some instancesit may be desired to. resurface or surface an old roaid or street, or to eliminate the prime coat. In such case the supporting course A'as shown in Figures 7, is punctured by rolling with the roller 1 0.to form sumps C therein. The top course D is then applied directto the supporting course and the cones E formed by the asphalt fl owing into said sumps. By this arrangement the top. course is locked to the supporting course. De GIIClID u on the orosit and softness of'the supporting course, the asphaltic oil will penetrate the walls of the sumps to a more or less extent, and thus establish by cohesion a bond therewith. By spreading mineral aggregate on the prime coat B a layer of mineral aggregate is thus embedded in the pavement and this tends to bind the. coat B and course D together between the. cones.

It is-pointed out thatwhen the mineral aggregate which has been spread uponthe layer D is rolled it will. be forced down into the cones thus stabilizing-themand also reinforcing said cones against lateral strains.

lVhat I claim,- is: V

1. The method of paving which consists in applying a prime. coat ofhot liquid asphalt to the top.- surface of a soft supporting course, then puncturing said coat and pene= trating the underlying surface of the support; ing co urse', and then applying a layer of hot liquid asphalt to the prime coat and flowing JACKSON F. WITT. 

